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motor and prop for p38

Old 03-15-2010, 04:58 PM
  #1  
leadtongue
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Default motor and prop for p38

I have a nitroplanes 51.5" p38.....i will be using two spectrum ar500 recievers and two eflite 40amp pro esc's...powering 4servos and 3 servos respectively. i have on hand 2 eflite power10 and 2 eflite power25 motors which i could use..I am estimating auw weight to be around 4-4.75. lbs when finished including motors and batteries....probably 2flightmax 2200 mah in parallel in each nacelle. I like scale looking 3 blade props and was thinking 9x7x3's with the power 25...it would pull about 22amps and provide about 50oz static thrust. The power 10's however with 9x5x3's would pull about about 28amps and provide about 51oz of static thrust...amp draw would be a little close though. Are the 25's overkill? I like the low amp draw...but the eflite stearman and the xt pulse25e have caught my eye also and the 25's would be perfect for those two models.I thought i had a solution with the 10's and some gws 3 blades til i realized that the max rpms are so incredibly low they would probably have broken! I saw a video of this plane with a welgard 2217-09 motor flying very spritely but looking at the specs one would think underpowered....especially if one motor quit! Any suggestions for the 10's....stay with the 25's?...or go with something else entirely?.
Old 03-15-2010, 05:28 PM
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DaveFlynn
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Default RE: motor and prop for p38

With the Master Airscrew 9x7 3-blade you can go counter-rotating.
Old 03-22-2010, 01:37 PM
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leadtongue
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Default RE: motor and prop for p38

Boy this plane is really nose heavy! I just may buy two reciever packs and place them as far back as i can! I decided to go with the monsterpower 25's .....i should be able to fly it with just one motor running....Got a pair of 10x4x3 props that are from the hangar9 alpha 40 and a couple of apc 2 blade props. All i have left to do is epoxy the tail and elevator sections, install servos,pushrods and horns...get a nice looking 3 blade spinner set....
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Old 04-12-2010, 02:23 PM
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leadtongue
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Default RE: motor and prop for p38

Well its almost done and the auw with two 2000mah lipos in parallel in each nacelle will be just under 5.25 lbs. that includes about 3.5 oz of weight to get correct cog. I will be using the 10x7 apce props for now. Control surface horns that came with kit are enormous! Probably are the same ones they are using in the 90' model. Those 10x4x3 props arent going to cut it im afraid...not enough thrust and did i mention they are about 2oz apiece. One word to anyone buying this model....i f you want any decent flight times your gonna need some large capacity batteries but finding the room is almost impossible. you would be better off gutting each nacelle and rebuild it around the batteries...also the servo tray was a little too high and servo is rubbing underside of one wing. Bolts for joining the center pod to the wing are drilled to far forward a good 3/8 of an inch off...you can tighten them down but it will pull the wing back with it and you will see gaps at leading edge of wings and the fuse and the two "****" that are at the leading edge of each wing will be perilously close to coming out of the precut slot in the center pod. The rear stabilizer is very flimsy,and the wood does not reach far enough under the taper...found that out when i traced it to cut off the monocote. So i just traced it on a new piece of balsa and made a new solid piece. Loads of power at half throttle...probably airborne in 15' from paved runway....hopefully will take off from grass. Foam wheels are...well...junk! I think ill be looking at some dubros. I cant get batteries out through bottom hatch...not enough opening....must charge them in the plane or remove the wings to change. I built a stand for it out of foam so i can take the wings off and it will cradle the two nacelles so as not to stress the end of fuse and stabilizer....a new threaded rod with wing nuts instead of phillips head bolt should make removing wings a snap....little carbon fibre rods and rubber gromets that they use to hold on heli canopies will expedite removing the supercharger covers. I saw a few different builds and noticed that there are different designs in the nacelle layout...not much but they may be roomier inside than mine. I purchased mine at toy sonic and it came with tanks for nitro motors so maybe i have an older version.

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